Circuit breaker with improved trip adjustment means

ABSTRACT

A circuit breaker, that comprises trip means automatically operable upon the occurrence of certain overload current conditions to trip the breaker and adjusting means selectively adjustable within a range of adjustment to adjust the trip means, comprises lock means or limit means selectively operable to change the range of adjustment.

United States Patent [72] Inventors James P. Ellsworth 2,445,426 7/ 1948 Gamel 335/45 Beaver; 2,806,924 9/1957 Olson 337/360 John Zipay, New Brighton, Pa. 3,084,236 4/ 1963 Klein 335/10 [211 App]. No. 703,409 3,110,848 11/1963 Hobson 335/273 [22] Filed Feb. 6,1968 3,179,769 4/1965 Ziegler 335/42 [45] Patented Apr. 20, 1971 3,260,822 7/1966 Stephenson 335/42 [73] Assignee Westinghouse Electric Corporation 3,391,361 7/ 1968 .Iencks 335/ 176 Pittsburgh Primary Examiner-Harold Broome Attorneys-A. T. Stratton, C. L. McHale and W. A. Elchik [54] CIRCUIT BREAKER WITH IMPROVED TRIP ADJUSTMENT MEANS 35 Claims, 11 Drawing Figs.

[52] U.S.Cl 335/176 [51] lnt. H0lh 71/74 Field of Search 335/176, ABSTRACT: A ir uit breaker, that comprises trip means 42, l0, 38, 45, 273; 337/273, automatically operable upon the occurrence of certain overload current conditions to trip the breaker and adjusting [56] References cued means selectively adjustable within a range of adjustment to UNrrED STATES PATENTS adjust the trip means, comprises lock means or limit means 2,658,126 1 1/ 1953 Filliette 337/70 selectively operable to change the range of adjustment.

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WITNESSES INVENTORS James P. Ellsworth 0nd John Zipoy WE JQMAM ATTORNEY PATENTED APRZO l9?! SHEET 2 OF g 5 O 2 f mwu F25 m 575 DB 9 W/,, m a 7 J w G i r Ill W F 1 I M y K 7 s m m m F v \N m CIRCUIT BREAKER WITH IMPROVED TRIP ADJUSTMENT MEANS CROSS-REFERENCE TO RELATED APPLICATIONS BACKGROUND OF THE INVENTION For certain applications, it is desirable to provide a circuit breaker with adjusting means adjustable, within a predetermined range of adjustment, to adjust the tripping characteristics of the circuit breaker, and with means for selectively varying the range of adjustment. For example, in order to use a particular circuit breaker for motor circuit protection it may be required that the breaker be arranged so that the breaker cannot be set to carry current of a value higher than a predetermined value without tripping. It may be desirable, for example, to provide that the trip adjustment cannot be set higher than l3 times the full load current of the motor that is to be protected by the breaker. It may be desirable for other applications to provide that the circuit breaker trip adjustment cannot be set to trip the breaker when a current lower than a predetermined value is carried by the breaker. Since a manufacturer may not know where or how the circuit breaker will eventually be used when the breaker is being manufactured, it is desirable to provide a circuit breaker with adjusting means selectively adjustable within a range of adjustment and with means for varying the range of adjustment so that the customer can vary the range of adjustment to suit the insulation requirements. Thus, an object of this invention is to provide an improved circuit breaker with means for selectively changing the range of trip adjustment of the breaker.

SUMMARY OF THE INVENTION A circuit breaker comprises an insulating housing and a circuit breaker mechanism supported within the housing. The circuit breaker mechanism comprises a pairof cooperable contacts and trip means operable automatically upon the occurrence of certain overload currents to eh'ect opening of the contacts. The trip means comprises a stationary magnetic memberand an armature structure spaced from the stationary magnetic member by an air gap and movable to diminish the air gap to trip the breaker. Adjusting means comprises an adjusting cam member rotatable about an axis normal to the front and back of the circuit breaker to cam the armature structure to change the dimension of the air gap to thereby adjust the tripping characteristics of the circuit breaker. The housing is provided with an opening at the front thereof, and the adjusting cam member comprises an actuating part accessible at the front opening to permit adjustment of the tripping characteristics. The adjusting cam member is rotatable to selectively adjust the tripping characteristics within a predetermined range of adjustment. The adjusting cam member is provided with an annular slot in the front thereof, and the housing is provided with a plurality of separate openings positioned over the annular slot. The adjusting cam member is provided with a stop portion, and movement of the adjusting cam member can be limited by placing a stop member through any of the separate openings to project the stop member down into the slot where the stop member will engage the stop surface on the adjusting cam member to limit rotational movement of the adjusting cam member to thereby vary or change the range of adjustment of the circuit breaker. The housing and stop member can be constructed so that the stop member will be permanently locked in position when the stop member is inserted into any of the separate openings; or the circuit breaker can be constructed such that the stop member can be removably mounted in any of the separate openings to permit further changes of the range of adjustment. For certain applications, the adjusting cam member can be set at the high point of the cam to provide that the circuit breaker will trip at a low predetermined overload, and the stop member can be positioned through the desired separate opening into the slot of the cam-adjusting member in the direction of the low point of the cam to thereby limit movement of the armature structure in the opening direction so that a worker will not be able to adjust the breaker to carry current higher than a predetermined current value. The adjusting cammember is also provided with a plurality of notches at the front thereof spaced along the path of the slot, and a barrier member can be selectively placed in any of the notches to serve -:as an additional stop member to limit movement of the adjusting cam member, for example, in the direction diminishing the air gap to thereby provide that a worker will not be able to adjust the circuit breaker to trip at a current lower than a predetermined current value. The circuit breaker is constructed such that the selected adjustment with the barrier member is made while the cover of the two-part insulating housing of the breaker is off of the breaker. It can be understood that either the stop member or the barrier member can be used with each of these members being usable to limit either an increase or decrease in the magnetic air gap; or that both of these members can be used with one of the members used to selectively determine the maximum air gap and the other used to selectively determine the minimum air gap. Although the invention is disclosed as applied to a circuit breaker with only an electromagnetic trip device, it can be understood that the invention could be utilized in a circuit breaker with a thermal trip device or with both a thermal and an electromagnetic trip device. The invention, as disclosed, is embodied in a mutlipole circuit breaker with an electromagnetic trip in each pole and with a common adjusting bar for simultaneous adjustment of the air gaps in all of the poles, which circuit breaker comprises a single adjusting means for operating the common adjusting bar.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a top plan view, with parts broken away, of a multipole circuit breaker constructed in accordance with principles of this invention;

FIG. 2 is a sectional view taken generally along the lines lI-II of FIG. I;

FIG. 3 is a partial sectional view taken generally along the line III-III of FIG. 1;

FIG. 4 is a sectional view, with partsbroken away, taken generally along the line lV-IV of FIG. 1;

FIG. 5 is an exploded view, partly in section and with parts broken away, of parts of the trip and adjusting structure seen in FIGS. 3 and 4;

FIG. 6 is a top plan view of the adjusting cam member seen in FIG. 5;

FIG. 7 is a top plan view of the support member seen in FIGS. 3 and 4;

FIG. 8 is a top plan view of the trip bar seen in FIGS. 25;

FIG. 9 is a side elevational view of the stop member seen in FIG. 4;

FIG. I0 is a side elevational view of a barrier member that may be used to change the range of trip adjustment; and

FIG. 11 is a view similar to FIG. 6 with the barrier member of FIG. 10 shown in section mounted on the adjusting cam member.

DESCRIPTION OF THE PREFERRED'EMBODIMENT Referring to the drawings, there is shown, in FIGS. 1 and 2, a three-pole circuit breaker 3 comprising an insulating housing 5 and a circuit breaker mechanism 7 supported in the housing 5. The housing 5 comprises an insulating base 9, having a generally planar back, and an insulating front cover 11 secured to the base 9. The housing 5 comprises insulating barrier means 12 separating the housing into three adjacent side-by-side pole unit compartments in a manner well known in the art.

The circuit breaker mechanism 7 comprises a single.

operating mechanism 13 and a single latch mechanism 15. The circuit breaker mechanism 7 also comprises a separate electromagnetic trip device 17 in each of the three-pole units.

A stationary contact 19; a movable contact 21 and an arcextinguishing unit 23 are provided in each pole unit of the breaker. The stationary contact 19 for each pole unit is fixedly mounted on the inner end of a conducting strip 25 that extends outward to an external cavity where a solderless terminal connector 27 is secured to the outer end of the member 25. The movable contact 21 for each of the pole units is mounted on a conducting contact arm 29 that is pivotally mounted, by means of a pin 31, on a switch arm 33 that is fixedly secured to an insulating tie bar 35. The switch arms 33 for all three of the pole units are secured to the common tie bar 35 for common movements with the tie bar that is pivotally mounted, by means of suitable pivot pins, on the side walls of the breaker housing. Suitable spring means (not shown) in each pole unit biases the associated contact arm 29 in a clockwise (FIG. 2) direction about the associated switch arm 33 to provide contact pressure in the closed position of the contacts. Suitable stop means is provided to limit clockwise movement of the contact arm 29 on the associated switch arm 33.

The single operating mechanism 13 is positioned in the center pole unit of the three-pole circuit breaker. The operating mechanism 13 is supported on a pair of spaced metallic rigid supporting plates 41 that are fixedly secured to the base 9 in the center pole unit of the breaker. An inverted U-shaped operating lever43 is pivotally supported on the spaced plates 41 with the inner ends of the legs of the lever 43 positioned in U-shaped notches in the plates 41. An insulating operating member 45, comprising an insulating shield 47 and an insulating handle part 49, is fixedly secured to the front portion of the operating lever 43. The handle 49 protrudes out through an opening 51 in the front of the cover 11, and the shield 47 closes the opening 51 in all positions of the handle.

The switch arm 33 for the center pole unit is operatively connected, by means of a toggle comprising toggle links 53 and 55, to a releasable trip member 57 that is pivotally supported on the supporting plates 41 by means of a pin member 59. The toggle links 53, 55 are pivotally connected together by means of a knee pivot pin 61. The toggle link 53 is pivotally connected to the switch arm 33 of the center pole unit by means of a pin 63, and the toggle link 55 is pivotally connected to the releasable trip member 57 by means of a pin 65. Overcenter springs 67 are connected under tension between the knee pivot 61 and the bight portion of the operating lever 43. Y

The contacts are manually opened by movement of the handle 49 in a counterclockwise (FIG. 2) direction from the on to the off" position. This movement carries the line of action of the overcenter springs 67 to the left causing collapse, to the left, of the toggle 53, 55 to thereby rotate the tie bar 35 in a counterclockwise direction to simultaneously move the three switch arms 33 to the open position opening the contacts of the three-pole units. The contacts are manually closed by reverse movement of the handle 49 from the ofi to the on" position, which movement moves the line of action of the overcenter springs 67 to the right to move the toggle 53, 55 to the position seen in FIG. 2, which movement rotates the tie bar 35 in a clockwise direction to move the switch arms 33 of the three-pole units to the closed position seen in FIG. 2.

The releasable member 57 is latched in the position seen in FIG. 2 by means of the latch mechanism 15. The latch mechanism is of the type more specifically described in the copending US. Pat. application of Nick Yorgin et a]. Ser. No. 621,321 filed Mar. 7, 1967. Thus, only a brief description of the latch mechanism is given herein. The latch mechanism 15 comprises a roller latch member 71 and an insulating trip bar 73. The roller latch member 71 comprises a generally U- shaped main body part 75 and a roller member 77 movably supported for limited travel in a pair of slots in the opposite legs of the part 75. A torsion spring 81 biases the roller member 77 to one end of the slots. The roller latch member 71 is pivotally supported on the supporting plates 41 by means of a pin member 83. The free end of the trip member 57 moves within a slot in the bight portion of the part 75.

The trip bar 73 (FIGS. 2, 4 and 8) is a molded insulating member formed to provide a pair of insulating pin portions 88 that are disposed in suitable openings in the supporting plates 41 to pivotally support the trip bar 73. The trip bar 73 is provided with a latch part 89 for engaging the bight portion of the main body part 75 of the roller latch member 71 to latch the roller latch member 71 in the position seen in FIG. 2. A compression spring 93 is positioned between the latch member 71 and the trip bar 73 to bias the trip bar 73 in the latching direction. As can be seen in FIG. 2, the releasable trip member 57 is provided with a hook portion at the free end (on the left as seen in FIG. 2) thereof for engaging the roller 77 to latch the trip member 57 in the position seen in FIG. 2.

There is a separate electromagnetic trip device 17 in each pole unit. Each of the electromagnetic trip devices 17 comprises a stationary magnetic core member 95, an armature structure 97 and a coil 99. Each armature structure 97 comprises a magnetic armature 101, an armature extension 103 secured to the armature 101 by means of a pivot pin 105 and a screw 107 threaded into a tapped opening in the upper end of the extension 103. Each armature structure 97 is biased to the initial position seen in FIG. 2 by means of a tension spring 109 that engages an arm portion of the armature 101 at one end thereof and a magnetic generally L-shaped member 113 at the other end thereof. As can be seen in FIG. .2, the armature structure 97 is positioned in the initial position with an air gap between the armature 101 and the stationary magnetic core 95. The armature 101 is pivotally supported at the left end thereof on an extension of the L-shaped magnetic member 113. The spring tension of each spring .109 can be adjusted by bending the upper spring support part of the associated member 113. As will be understood with reference to FIGS.- 2-5 and 8, the insulating trip bar 73 is provided with a separate cavity for each pole unit with a separate actuating surface 117 as the bottom surface of each cavity. In each pole unit the upper part of the armature extension 103 is positioned just over the associated cavity so that the associated screw 107 is positioned above the associated actuating surface 117 of the trip bar 73.

In the closed position of the circuit breaker, the circuit through each pole unit extends from a solderless terminal connector 119 through a conducting strip 121 to a coil lead 122, through the coil 99, a coil lead 123, a flexible conductor that is secured at one end thereof to the coil lead 123 and at the other end thereof to the associated conducting contact arm 29, the contacts 21, 19, the conducting strip 25 to the other solderless terminal connector 27.

When the circuit breaker is in the latched position seen in FIG. 2, the tension springs 67 operate through the toggle link 55 and pivot 65 to force the trip member 57 in a clockwise (FIG. 2) direction about the pivot 59. Clockwise movement of the trip member 57 is restrained by the engagement of the free end thereof under the roller member 77 of the roller latch 71 with the trip member 57 pulling the roller latch 71 in a clockwise direction about the pivot 83. Clockwise movement of the roller latch 71 about the pivot 83 is restrained by the engagement of the roller latch 71 with the latch part 89 of the trip bar 73. The force of the roller latch 71 against the latch part 89 of the trip bar 73 operates through the axis of the pivot of the trip bar 73 so that clockwise movement of the roller latch 71 is restrained by the trip bar 73 without tending to move the trip bar 73 about the axis of the pivotal support 88 of the trip bar 73. Thus, the trip bar 73 is in a neutral or latching position latching the roller latch 71 and trip member 57 in the latched position seen in FIG. 2.

The circuit breaker is shown in the closed and latched position in FIG. 2. Upon the occurrence of an overload current above a predetermined value in any of the pole units,

the armature 101 is attracted toward the associated stationary magnetic member 95 whereupon the armature 101 pivots in a clockwise (FIG. 2) direction closing the air gap between the magnetic members 95, 101 and pulling the armature extension 103 downward. Near the end of this downward movement of the armature extension 103, the screw 107 engages the actuating surface 117 (FIG. 5) of the trip bar 73 to rotate the trip bar 73 in a counterclockwise (FIG. 2) direction moving the latch part 89 of the trip bar 73 to a position releasing the roller latch 71. Upon release of the roller latch 71 the springs 67 (FIG. 2) operate to rotate the trip member 57 in a clockwise direction about the pivot 59 with the roller latch 71 moving in a clockwise direction about the pivot 83. The trip member 57 moves in a clockwise direction to the tripped position which movement is limitedby engagement of the trip member with a suitable stop in the supporting frame plates 41. During movement of the trip member 57 to the tripped position, the toggle 53, 55 collapsesrotating the switch arm 33, that is attached to the lower toggle link 53, to move the tie bar 35 and all three of the switch arms of the three-pole units in a counterclockwise direction to simultaneously open the contacts of the threepole units. During this movement, the handle 49 is moved to a position intermediate the off"and on" positions in a well-known manner to provide a visual indication that the circuit breaker has been tripped.

Before the circuit breaker can be manually operated after an automatic tripping operation, the circuit breaker mechanism must be reset and relatched. Resetting is effected v by movement of the handle 49 from the intermediate position to the full off position. During this movement, a part 133 on the operating lever 43 engages a shoulder portion 135 on the trip member 57 to rotate the trip member 57 in a counterclockwise direction about the pivot 59. During this movement, the free end of the trip member 57 moves down in the slot in the bight portion of the main part 75 of the roller latch 71 and the end part of the trip member 57 engages the roller 77 moving the roller 77 in the slots in which the roller member 77 is seated to wipe past the roller member 77, and when the end part of the releasable member 57 passes the roller 77 the spring 81 biases the roller 77 back to the position seen in FIG. 2. During this resetting movement of the trip member 57., the end part thereof engages a surface at the bottom of the slot in the bight portion of the main body part 75 of the roller latch 71 to move the roller latch 71 in a counterclockwise direction about the pivot 83 to the position seen in FIG; 2. As the roller latch 71 reaches the position seen in FIG. 2, a part of the roller latch clears the hook or latch part 89 of the trip bar 73 whereupon the spring 93 biases the latch part 89 into latching engagement with the roller latch 71 to latch the roller latch 71 in the position seen in FIG. 2. Thereafter, upon release of the handle 49 by the operator, the springs 67 again bias the toggle link 55 to bias the trip member 57 in a clockwise direction to move the trip member up to engage the roller 77 in the latched position seen in FIG. 2. Thereafter, the handle 49 can be manually moved between the ofF' and the on" positions to operate the contacts in the manner hereinbefore described. A more detailed description of the tripping operation is set forth in the above-mentioned copending US. application of Nick Yorgin et al. Ser. No. 621,321, now Pat. No. 3,460,075.

Improved means is provided for adjusting the trip means of the circuit breaker. As can be seen in FIGS. 4 and 5, an elongated adjusting bar 133 comprises an elongated bar 135 and a pair of supporting arms 137 secured to the bar 135 by means of rivets 139. Each of the supporting anns 137 is provided with an opening 141 for receiving a molded pin portion 143 (FIG. 8) of the trip bar 73 to pivotally support the adjusting bar 133 on the pins 143. The adjusting bar 133 movesabout an axis aligned with the axis of movement of the trip bar 73. The elongated bar 135 is provided with a separate opening 145 for each of the screws 107 of the three-pole circuit breaker. Each of the openings 145 is of a large enough dimension to permit the associated screw 107 to move vertically and laterally relative to the bar 135.

Referring to FIG. 4, a supporting plate 151 is fixedly secured to the base 9 in one of the outer pole'units (the lower one as seen in FIG. 1). A first inverted generally L-shaped bracket 153 is fixedly secured to the plate 151 to support'an insulating adjusting cam member 155. The insulating adjusting cam member 155 (FIGS. 5 and 6) comprises a lower cylindrical part 157 that fits, for rotation, in a suitable opening in one leg of the supporting member 153 (FIG. 3); a cam surface 159; a part 161 having a slot 163 and a plurality of indentations 165 in the top or front part thereof; and a front part 167 having a slot 169 therein. As can be seen in FIG. 4, another generally L-shaped support member 171 is connected to the first support member 153 by means of a screw 173. A spring member 175 biases the adjusting member 155 upward or frontward (FIG. 4) and the part 161 of the adjusting member 155 engages the member 171 to limit the upward movement of the adjusting cam member 155. The part 167 of the adjusting cam member 155 protrudes through an opening 176 (FIG. 7) in the member 171 and through an opening 177 (FIGS. 3 and 4) in the front part 11 of the circuit breaker housing. The member 171 (FIG. 7) is provided with a plurality of openings or notches 179 that align with a plurality of openings 181 (FIGS. 1, 3 and 4) in the housing part 11 to receive a locking pin in a manner to be hereinafter described. The member 171 (FIGS. 4 and 7) is provided with a bent over end projection 185 that extends down into the slot 163 in the adjusting member 155. As can be seen in FIG.'6, the slot 163 does not complete a circle in that the member 155 is provided with a surface 187 that extends up higher than the base of the slot 163 to provide a first stop 189 and a second stop 191 for engaging the projection 185 (FIGS. 3 and 7) to limit rotational movement of the member 155. The member 171 (FIG. 7) is provided with an indentation 193 that protrudes from the lower surface thereof to index the adjusting member 155 that is biased frontward (FIG. 3) to position the indentation 193 in one of the notches 165 of the adjusting member 155.

During the assembly of the circuit breaker, in addition to the hereinbefore mentioned adjustment of the spring tension of each of the springs 109, two adjustments are made before the cover 11 is mounted on the base 9, and a third common adjustment can be made externally after the cover 11 is mounted on the base 9. With the cover 11 removed, the adjusting member 155 is rotated to the setting which provides the maximum air gap, which setting is the setting where the low part of the cam surface 159 engages a surface 195 on the arm 137 (FIGS. 35) that supports the adjusting bar 135. The adjusting member 155 is in this position when the projection I85 (FIGS. 3 and 7) on the member 171 engages the stop surface 189 (FIG. 6) on the adjusting member 155. Each of the separate screws 107 (FIGS. 4 and 5) is then adjusted so that the screw 107 will engage the surface 117 and move the trip bar 73 to a tripping position at the end of the armature movement. The adjustment of the screw 107 is such that the screw does not pick up the trip bar 73 during the initial armature movement so that there is no resistance from the latching trip bar during the initial armature movement, and

' the screw adjustment 107 must be such that before the end of the armature movement the screw will in fact move the trip bar to a tripping position. Each of these adjustments of the screw 107 on the armature extension 103 is made by rotating the screw 107 to vary the relative position of the head of the screw 107 relative to the associated surface 117 on the trip bar 73. After adjustment of the screws 107 on the armature extensions 103, the individual magnetic air gaps are adjusted so that each pole unit will magnetically trip at a predetermined current. This adjustment is made by a separate nut 199 on each of the screws 107. The nut 199 is rotated on the associated screw 107 to engage the lower surface of the bar 135, and the surface 195 of the adjusting bar structure 133 engaging the cam surface 159 of the adjusting member 155 to limit clockwise (FIG. 3) movement of the adjusting bar structure 133, as the nut 99 is moved upward on the associated screw 107 the associated armature structure 97 is moved downward to reduce the associated magnetic airgap between the associated armature 101 and the associated stationary magneticmember 95. For example, if it is desirable to provide a circuit breaker wherein the maximum trip setting is 80 amps, each of the nuts 199 is rotated to move upward against the common adjusting bar 135, the adjusting bar 135 being restrained from clockwise movement by engagement (FIGS. 3 and of the surface 195 with the low point off the cam surface 159, to move the associated armature structure 97 downward to reduce the associated magnetic air gap until the circuit breaker trips with a current of 80 amps passing through the associated pole unit that is being adjusted. Each of the air gaps is thus individually adjusted with current flowing through the associated pole unit to trip the circuit breaker at 80 amps. After the adjustment of each screw on the associated armature extension 103, the screw can be cemented in the adjusted position; and after the adjustment of each nut 199 on the associated screw 107 the nut can be cemented in the adjusted position. Thereafter, the cover 11 can be moved into position and secured to the base 9 by means of a plurality of screws 201 (FIG. 1).

With the cover 11 in the mounted position, the three trip units can be simultaneously adjusted by operation of the single adjusting member 155. With the adjusting member 155 positioned such that the low point of the cam 159 engages the surface 195 of the adjusting bar structure 133, a current of the predetermined value such, for example, as 80 amps through any of the three-pole units will operate the electromagnetic trip device in that pole unit to rotate the trip bar 73 to the tripped position to effect a tripping operation in the manner hereinbefore described. When it is desired to provide that the circuit breaker will trip upon the occurrence of a lesser overload current, a screwdriver is placed in the slot 169; a downward force is applied to the screwdriver to move the adjusting member 155 downward to release the notch 165 (FIG. 6) from the indentation 193 (FIG. 7); and the screwdriver is rotated in a clockwise (FIG. 6) direction to a lower-trip setting whereupon the downward force against the screwdriver can be released so that the spring 175 (FIG. 3) will bias the adjusting member 155 upward to position another of the notches 165 in a nested relationship with the indentation 193 (FIG. 7) to stabilize the adjusting member 155 in the newly adjusted position. As can be understood with reference to FIG. 6, as the adjusting member 155 is rotated in a clockwise direction the distance between the axis of the adjusting member 155 and the surface of the cam 159, that is opposite the surface 195 (FIG. 5) of the adjusting bar structure 133, increases so that clockwise movement of the adjusting member 155 moves the adjusting bar structure 133 in a counterclockwise (FIGS. 4 and 5) direction. As the adjusting bar structure 133 moves counterclockwise the bar 135 engaging the three nuts 199 moves the three armature structures 97 downwardly to reduce the magnetic air gaps of the three electromagnets. Clockwise (FIG. 6) adjusting movement of the adjusting member 155 is limited when the stop surface 191 engages the stationary projection 185 that is disposed in the slot 163. It can be understood with reference to FIG. 6 that when the stop surface 191 engages with projection 185 (FIGS. 4 and 7) the high point of the cam 159 is opposite the surface 195 (FIG. 5) so that the adjusting bar structure 133 will be at the maximum counterclockwise adjusted position and the three armature structures 97 will be at their lowest positions so that the magnetic air gaps will be adjusted to the minimum dimension. When the armature structures 97 are adjusted to provide the minimum magnetic air gaps the circuit breaker will trip when a minimum of overload current such, for example, as 30 amps passes through any of the three-pole units of the circuit breaker. The surface 195 of the adjusting bar structure 133 is biased against the cam surface 159 by the three springs 109 (FIG. 2) of the three-armature structures 97 which springs bias the armature structures toward the open position to bias the nuts 199 FIGS. 4 and 5 into engagement with the adjusting bar structure 133 to thereby bias the adjusting bar 133 in a clockwise (FIG. 2, 3

and 5) direction. Suitable indicating means may be provided on the front of the circuit breaker (FIG. 1) to indicate at which current the circuit breaker will trip when the adjusting member is in each of the positions indexed by each of the notches 165. As can be understood with reference to FIGS. 2- -5 and 8, the adjusting bar structure 133 pivots on the pins 143 (FIG. 8) about the same axis that the trip bar 73 pivots, with the trip bar 73 being mounted on the supporting plates 41 (FIG. 2) for pivotal movement about the pin 88 (FIG. 8). It can be understood that by adjusting the tripping characteristics of the circuit breaker by moving an adjusting bar 133 that moves relative to the trip bar 73, the trip bar 73 does not move during adjustment so that the amount of latch engagement between the latch part 89 of the trip bar 73 and the roller latch 71 (FIG. 2) is not varied or disturbed by the trip adjustment.

As was previously set forth, when the adjusting cam member 155 is rotated counterclockwise (FIG. 6) this counterclockwise movement will be limited when the surface 189 on the adjusting cam member 155 engages the projection on the support member 171. At this first or high adjustment position, the low point of the cam surface 159 engages the surface (FIG. 5) of the adjusting bar structure 133 to limit clockwise movement of the adjusting bar structure 133, and the armature structure 97 is at the uppermost position so that the three air gaps are at their maximum dimensions. When the air gaps are at their maximum dimensions the circuit breaker is adjusted so that the breaker will carry the highest overload current prior to tripping, and the breaker will trip when this highest overload current is reached in any of the three-pole units. When the adjusting cam member 155 is rotated clockwise (FIG. 6) this clockwise movement is limited by engagement of surface 191 with the projection 185 in which position the high point of the cam 159 is adjacent the surface 195 of the adjusting bar structure 133 so that the adjusting bar structure 133 is pivoted to the furtherest counterclockwise (FIG. 5) position and the three armature structures 97 are positioned at their lov/ initial positions so that the three air gaps are at their minimum dimensions. When the air gaps of the three electromagnets are at their minimum dimensions the circuit breaker will trip when the predetermined low overload current passes through any of the three-pole units. Thus, the adjusting means is selectively adjustable within a predetermined range of adjustment which range of adjustment extends from the low-trip setting or adjustment to the high-trip setting or adjustment. A locking pin or limit member 205 (FIG. 9) is provided for selectively changing the range of adjustment of the tripping means. As previously set forth, a plurality of openings 181 are provided in the front of the insulating housing aligned with the front slot 163 of the adjusting cam member 155. The notches or openings 179 (FIG. 7) in the support member 171 are aligned with the openings 181 (FIG. 1) in the housing. When it is desired to change the range of adjustment, the limit member 205 is inserted through one of the openings 181 in the housing and through the aligned notch or opening 179 in the support member 171 to extend down into the slot 163 of the adjusting cam member 155 to engage one of the stop surfaces 189 or 191 of the adjusting cam member 155 to limit adjusting movement of the adjusting cam member 155. Although the limit member 205 could be used to raise the low-trip characteristic of the trip means by being placed into position when the adjusting cam member 155 is at the high-trip position so that the limit member 205 will engage the stop surface 191 to limit clockwise (FIG. 6) movement of the adjusting cam member 155 to thereby limit the adjustment in the low-trip direction, the invention has particular utility when the limit member 205 is used to determine or limit the hightrip adjustment. As was previously set forth, for certain applications of circuit breakers it is desirable to provide that the high-trip adjustment be such that the adjustment cannot be set higher than 13 times the full load current of the motor that the circuit breaker is used to protect. Thus, a customer can purchase the circuit breaker and at the installation the customer can determine the full load current of the motor that is to be protected and then selectively limit the high-trip adjustment of the range of adjustment with the use of the limit member 205. For example, if the circuit breaker is calibrated to have a range of adjustment from a high-trip adjustment of 80 amperes to a low-trip adjustment of 30 amperes and if the circuit breaker is to be used to protect a motor having a full load current of 4 amperes, it will be necessary to change the range of adjustment so that the high-trip adjustment cannot be set higher than 52 amperes which is l3 times the full load current of 4 amperes. As shown in FIG. I, the predetermined characteristics of the circuit breaker are such that the locking pin or limit member 205 can be used to limit the high-trip adjustment to 80, 70, 60, 50, 40 or 30 amperes. ln theexamplc being described, since it is necessary to limit the range of adjustment such that the breaker cannot be set to have a hightrip setting or adjustment higher than 52 amperes and because the available limit opening 181 is 50 amperes, this breaker would be selectively adjusted to provide that the breaker cannot carry current higher than 50 amperes without tripping. In order to limit the high-trip setting to 50 amperes, the adjusting cam member 155 is first rotated clockwise (FIG. 6) to the low-trip adjustment where the stop surface 19! engages the projection I85. Thereafter. the limit member 205 is placed down through the selected opening I81 indicated by 50 in FIG. I to thereby provide a stop in the slot I63 (FIG. 6).

Thereafter, when the adjusting cam member 155 is rotated counterclockwise increasing the magnetic air gaps this counterclockwise movement will be limited when the stop surface 189 (FIG. 6) engages the limit member 205 limiting further enlargement of the air gaps. Thus, the range of adjustment of this circuit breaker will be from a low-trip adjustment of 30 amperes to a high-trip adjustment of amperes.

The limit member 205 (FIG. 9) is a plastic pin member with the center part 209 (intermediate the opposite ends thereof) having a slightly larger diameter than the opposite end parts, and with the pin member 205 being selected such that the member must be forcefully moved down through the associated opening 181 to a position (FIG. 4) where the enlarged part 209 is just below the under surface of the insulating cover so that once the member 205 is forced into position the member 205 cannot be removed from the circuit breaker. Thus, once the range of adjustment has been changed at the installation a worker cannot remove the member 205 to raise the high-trip point of the range of adjustment. It can be understood, however, that the pin member 205 could be constructed such that the member could be readily removed so that the range of adjustment could be changed at the installation.

If desired, a paper member 211 (broken away in FIGS. 3 and 4) could be bonded to the front of the housing to cover the openings 1181. The paper member 211 is provided with an opening aligned with the operating part 167 of the adjusting cam member 155 to permit external operation of the adjusting cam member 155. The paper member 211 is provided with indications on the front thereof indicating where the particular openings 18! are located and with the indications identifying the trip adjustment that the breaker would have if the locking pin were placed through the indicated openings. In this case, at the installation a worker could use a sharp tool and pierce the paper just over the selected opening 181, and thereafter the limit member 205 could be forced down through the pierced paper into the selected opening.

Another means for changing the range of adjustment is disclosed in FIGS. 10 and II. As can be seen in FIG; 11, the adjusting cam member 155 is provided with a plurality of pairs of notches 215 spaced along the slot 163. Abarrier member 2I7 can be selectively positioned in any of the pairs of notches 215 to serve as a stop to engage the stop surfaces 189 or 191 to limit adjusting movement of the adjusting cam member 155. The barrier 217 is placed into the selected limiting position when the cover II of the circuit breaker is removed.

The cover 11 is then mounted on the circuit breaker and secured in place whereupon the barrier 217 cannot be removed unless the cover of the breaker is removed. The barrier 217 can be used to limit either the high-trip setting or the low-trip setting in the same manner as the limit member 205. It is to be understood that when either of the members 205 or 217 is moved into the selected position, the adjusting cam member 155 should be in a predetermined position so that the barrier or limit member will limit movement in the desired or selected direction of adjusting movement of the adjusting cam member 155. For example, when it is desired to set either of the limit members 205 or 217 into position to limit the low-trip setting the adjusting cam member 155 should be at the high-trip adjusted position and when it is desired to use either of the limit members 205 or 217 to limit the high-trip setting the adjusting cam member 155 should be at the low-trip adjusted position thereof. It is to be understood that either of the limiting members 205 or 217 could be used to limit either the high-trip setting or the low-trip setting; or two of either of the members 205 or 317 could be used to limit both the high-trip setting and the low-trip setting; or one each of the members 205 and 217 could be used to limit the highand low-trip settings. As was previously set forth, the invention has particular utility when the limit member 205 is used to provide an external selective adjustment for changing the range of adjustment by limiting the high-trip setting of the circuit breaker.

As will be understood from the hereinbefore set forth description and the accompanying drawings, the stop -members or limit members 205 (FIG. 4) and 217 (FIG. 11)

change the range of adjustment (i.e., the limits of movement of the adjusting cam member 155) without affecting the tripping action of the trip means in response to the adjusted position of the adjusting cam member 155. In other words at a given position of the adjusting cam member 155 the trip means will trip the breaker at the same predetermined overload both before and after the range of adjustment is changed by either of the members 205 or 217. At a given position of the adjusting cam member 155, adjustment of either of the members 205 or 217 does not change the dimensions of the magnetic air gaps or the spring tension on the armatures of the trip means.

The circuit breaker herein described was provided with a range of adjustment between a low-trip adjustment of 30 amperes and a high-trip adjustment of amperes with a 40 ampere, 50 amperes, 60 ampere and 70 ampere adjustment in between the lowand high-trip adjustments. It is to be understood that this description was only byway of example and that a circuit breaker could be constructed in accordance with principles of this invention with more or less than six external adjustments and with a different range than the range between a 30 ampere low-trip adjustment and an 80 ampere high-trip adjustment.

We claim:

1. A circuit breaker comprising an insulating housing, a circuit breaker mechanism supported in said housing and comprising a pair of contacts, trip means operable automatically upon the occurrence of certain overload current conditions to automatically trip said circuit breaker opening said contacts, adjusting means selectively adjustable within a range of adjustment to adjust saidtrip means to trip said circuit breaker at a selected overload current within a range of overload currents, and limit means for selectively changing said range of adjustment without affecting the tripping action of said trip means in response to the adjusted position of said adjusting means such that at a given position of said adjusting means said trip means will trip said circuit breaker at the same predetermined overload current both before and after said range of adjustment is changed.

2. A circuit breaker according to claim 1, said adjusting means being externally accessible for operation from outside of said installation housing, and said limit means comprising an externally accessible limit member selectively movable to any of a plurality of limiting positions to change said range of adjustment.

3. A circuit breaker according to claim 1, said adjusting means comprising an adjusting member supported for adjusting movement about an axis, and said limit means comprising a limit member movable to a selected limiting position to stop said adjusting movement of said adjusting member to prevent adjusting movement of said adjusting member past a selected position.

4. A circuit breaker according to claim I, said insulating housing having opening means therein, said adjusting means comprising an adjusting member externally accessible at said opening means and supported for adjusting movement, and said limit means comprising a limit member selectively movable from outside of said housing to any of a plurality of selected limiting positions to change said range of adjustment.

5. A circuit breaker according to claim 1, said trip means comprising a stationary magnetic member and a movable armature structure in an initial position spaced from said stationary magnetic member by an air gap, upon the occurrence of an overload current above a predetermined value said armature structure being attracted to said stationary magnetic member and moving toward said stationary magnetic member to trip said circuit breaker, said adjusting means comprising an adjusting member supported for adjusting movement and being adjustably movable to change the initial position of said armature structure to change the dimension of said air gap, and said limit means being operable to change the range of adjusting movement of said adjusting member. 4

6. A circuit breaker according to claim 5, said adjusting member being supported for adjusting movement about an axis, and said limit means comprising a limit member movable to a limiting position to limit said adjusting movement of said adjusting member.

7. A circuit breaker according to claim 5, said adjusting member being externally accessible and operable from outside of said insulating housing, and said limit means comprising a limit member selectively positionable from outside of said housing in any of a plurality of positions to stop said adjusting movement of said adjusting member against movement past a position determined by the selected position of said adjusting member.

8. A circuit breaker according to claim 6, said housing having a first opening in the front thereof, said adjusting member comprising an operating part accessible at said first opening to permit external operation of said adjusting member, said housing having a plurality of separate openings therein in proximity to said first opening, said adjusting member having a stop surface thereon, and said limit member being selectively positionable in any of said plurality of separate openings in a limiting position in the path of movement of said stop surface to limit adjusting movement of said adjusting member.

9. A circuit breaker according, to claim 8, said circuit breaker comprising a multipole circuit breaker, said insulating housing comprising a plurality of barriers separating said housing into a plurality of compartments in a side-by-side relationship, said circuit breaker mechanism comprising a pole unit in each of said compartments with each of said pole units comprising a separate pair of contacts, a separate trip means in each of said compartments, each of said separate trip means being operable upon the occurrence of certain overload current conditions to effect a tripping operation of said circuit breaker simultaneously opening all of said pairs of contacts, and said adjusting member being movable to simultaneously adjust all of said trip means.

10. A circuit breaker according to claim 9, said adjusting member comprising an adjusting cam member having a cam surface thereon, a common adjusting bar cooperable with said cam surface and movable to simultaneously adjust said armature structures, said adjusting cam member having a slot therein open at the front of said adjusting member, a

stationary stop member positioned in said slot, said adjusting cam member having a pair of stop surfaces for engaging said stationary stop member to limit movement of said adjusting cam member in both directions about said axis, and said limit member being positionable in said slot through any of said separate openings to cooperate with at least one of said stop surfaces to limit movement in at least one direction of said adjusting cam member.

11. A circuit breaker comprising an insulating housing, a circuit breaker mechanism supported in said housing and comprising a pair of contacts, trip means operable automatically upon the occurrence of certain overload current conditions to trip said circuit breaker opening said contacts, externally accessible adjusting means adjustable from outside of said housing, said adjusting means being selectively adjustable within an initial range of adjustment to adjust said trip means to trip said circuit breaker at a selected overload current within a range of overload currents, and said circuit breaker being constructed and arranged to permit externally positionable limit means to be selectively positioned in any of a plurality of predetermined limiting positions to change said initial range of adjustment to a new range of adjustment within said initial range of adjustment.

12. A circuit breaker according to claim 11, said adjusting means comprising an adjusting member supported for adjusting movement about an axis, said adjusting member comprising stop means, and said circuit breaker being constructed and arranged such that a limit member can be selectively positioned thereon in a selected position of said plurality of predetermined limiting positions in the path of movement of said stop means to limit adjusting movement of said adjusting member.

13. A circuit breaker according to claim 12, said housing having opening means at the front thereof, said housing comprising a generally planar back, said adjusting member being supported for movement about an axis normal to said back and comprising an operating part accessible at said opening means in the front of said housing, said opening means in the front of said housing comprising a plurality of settings positioned such that when a limit member is positioned in a limiting position at any of said settings the limit member will be in the path of movement of said step means to limit movement of said adjusting member about said axis.

14. A circuit breaker according to claim 13, fixed projection means in said housing engaging said stop means of said adjusting member to limit movement in both directions of said adjusting member to provide said initial range of adjustment of said adjusting member, and said adjusting member comprising a cam member operating with a camming action upon rotation of said adjusting member to adjust the tripping characteristics of said circuit breaker.

15. A circuit breaker according to claim 11, said housing comprising an insulating housing having a plurality of barriers therein forming a plurality of compartments in a side-by-side relationship, said circuit breaker comprising a multipole circuit breaker with a separate pole unit in each of said compartments, each of said pole units comprising a pair of cooperable contacts, said trip means comprising a separate trip device in each of said pole units, each of said separate trip device comprising a stationary magnetic member and a movable armature structure in an initial position spaced from the associated stationary magnetic member by an air gap, a common adjusting bar common to all of said pole units and movable to simultaneously move said armature structures to simultaneously adjust the initial positions of all said armature structures, said adjusting member and said adjusting bar structure comprising cooperating earn parts whereby upon adjusting movement of said adjusting member said adjusting bar structure will be cammed to vary the initial positions of all of said armature structures.

16. A circuit breaker comprising an insulating housing, a circuit breaker mechanism supported in said housing and comprising a pair of contacts, trip means operable automatically upon the occurrence of certain overload current conditions to trip said circuit breaker opening said contacts, externally accessible adjusting means adjustable from outside of said housing, said adjusting means being factory set to provide selective adjustability within a range of adjustment from a low adjusted position to an initial high adjusted position to adjust said trip means to trip said circuit breaker at a selected overload current within a range of overload currents from a low-tripping overload current to an initial high-tripping overload current, and limit means comprising a limit member selectively positioned from outside of said housing in a selected position on said circuit breaker to provide a new high adjusted position of said adjusting means between said low adjusted position and said initial high adjusted position to provide that said adjusting means cannot be adjusted to a position higher than said new high adjusted position.

17. A circuit breaker according to claim 16, said trip means comprising a stationary magnetic member and a movable armature structure, said armature structure being spaced from said stationary magnetic member by an air gap and being actuated toward said stationary magnetic member to trip said circuit breaker, said adjusting member being supported for movement about an axis and being movable between said low adjusted position and said high adjusted position, said adjusting member comprising stop means, and said limit member comprising a stop member selectively positioned in the path of movement of said stop means.

' 18. A circuit breaker according to claim 17, said housing having opening means at the front thereof, said housing having a generally planar back, said adjusting member being supported for adjusting movement about an axis normal to the plane of said back, said adjusting member comprising an operating part accessible at said opening to permit external operation of said adjusting member, said adjusting member comprising stop means inside of said housing, said opening means at the front of said housing comprising a plurality of settings for receiving said limit member at any of said plurality of settings which limit member is positioned through a selected setting into the path of movement of said stop means to limit movement of said adjusting member.

19. A circuit breaker comprising an insulating housing, a circuit breaker mechanism supported within said housing and comprising a pair of contacts, current responsive electromagnetic trip means comprising a stationary magnetic member and an armature supported with an air gap between said stationary magnetic member and armature, upon the occurrence of overload currents above a predetennined value said armature being attracted to said stationary magnetic member and moving to effect automatic opening of said contacts, adjusting means externally operable from outside said housing to adjust said armature to thereby adjust said air gap, said adjusting means being movable between an initial low limit low-trip adjusted position wherein said air gap is diminished and an initial high limit high-trip adjusted position wherein said air gap is enlarged, stop means in said housing providing the initial limits of movement of said adjusting means at said initial low limit low-trip adjusted position and said initial high limit high-trip adjusted position to thereby provide an initial range of adjustment of said adjusting means between said initial low limit low-trip adjusted position and said initial high limit high-trip adjusted position, and extemallyroperable limit means selectively positionable on said circuit breaker to selectively provide a new high limit high-trip adjusted position between said initial low limit lowtrip adjusted position and said initial high limit high-trip adjusted position.

20. A circuit breaker according to claim 19, said insulating housing comprising a generally planar back, said adjusting means comprising an adjusting cam member movable about an axis normal to the plane of said back to adjust said armature with a camming action, said adjusting cam member comprising a stop part, and said limit means comprising a stop member selectively positionable in the path of movement of said stop part. v

21. A circuit breaker according to claim 20, said insulating housing having an adjusting member opening therein, said adjusting cam member comprising an actuating part accessible for operation at said adjusting member opening, said insulating housing having a plurality of stop-member openings therein spaced around said adjusting member opening, and said stop member being selectively positionable in a selected one of said stop-member openings into the path of movement of said stop part. I

22. A circuit breaker according to claim2l, and said'stop member being selectively and removable positionable in the selected stop-member opening. v

23. A circuit breaker according to claim 21, and said insulating housing and said stop member being constructed and arranged such that when said stop member is operatively;

positioned inthe selected one of said stop-member openings said stop member is removable only by destruction of parts or disassembly of said housing.

24. A circuit breaker according to claim 19, said circuit breaker being a multipole circuit breaker and comprising a pair of said contacts for each pole, a separate stationary magnetic member and armature for each pole, a common trip bar common to all of said poles, upon attraction of any of said armatures to the associated stationary magnetic member the attractedarmature operating to effect movement of said common trip bar to effect automatic opening of said contacts, said adjusting means being a single adjusting means externally operable from outside said housing to simultaneously adjust all of said armatures to thereby simultaneously adjust all of the air gaps between said armatures and their associated stationary magnetic members, and said externally operable limit means being a single externally operable limit means selectively positionable to simultaneously selectively provide the new high limit high-trip adjusted positions of all of said armatures.

25. A circuit breaker according to claim 24, said insulating housing having a handle opening in the front thereof, a handle protruding through said handle opening and being manually operable to simultaneously open and close the contacts of all of said poles, said adjusting means comprising an adjusting cam member supported for movement about an axis extending in the direction from front to back in said housing, said adjusting cam member being movable about said axis to simultaneously move all of said armatures with a camming action, said insulating housing having an'adjusting member opening in the front thereof, said adjusting cam member comprising an actuating part accessible for operation at said adjusting member opening, said adjusting cam member comprising a stop part, said insulating housing having a plurality of stop-member openings in the front thereof spaced around said adjusting member opening, and said limit means comprising a stop member selectively positionable in a selected one of said stop-member openings into the path of movement of said stop part.

26. A circuit breaker comprising a housing, a circuit breaker mechanism supported in said housing, said mechanism comprising a stationary contact, a movable contact, a releasable trip member releasable to effect automatic opening of said contacts, current responsive trip means automatically operable in response to overload current conditions to effect release of said releasable trip member, an externally operable adjusting member movable through a factory-set maximum range of movement from a minimum low-current trip position to a maximum high-current trip position to adjust said trip means, and an externally accessible stop member selectively positionable in a selected stopping position selectable from a plurality of stopping positions than a selected new high-current trip position between said minimum lowcurrent trip position and said maximum highcurrent trip position.

27. A circuit breaker according to claim 26, said adjusting means comprising an adjusting member supported for adjusting movement about an axis, said adjusting member comprising a stop part, and said externally accessible stop member being selectively positionable in the path of movement of said stop means to stop movement of said adjusting member at the selected new high-current trip position.

28. A circuit breaker according to claim 27, said housing having a handle opening in the front thereof, a handle protruding through said handle opening andbeing manually operable to open and close said contacts, said housing having an adjusting member opening in the front thereof, said adjusting member being supported for adjusting movement about an axis extending in the direction from front to back in said housing, said adjusting member comprising an actuating part accessible for operation at said' adjusting member opening, said housing having a plurality of stop-member openings therein in proximity to said adjusting member opening, and said stop member being selectively positionable in a selected one of said stop-member openings into the path of movement of said stop part.

29. A circuit breaker according to claim 28, and said stop member being selectively and removably positionable in the selected stop-member opening.

30. A circuit breaker according to claim 28, and said housing and said stop member being constructed and arranged such that when said stop member is operatively positioned in the selected one of said stop-member openings said stop member is removable only by destruction of parts or disassembly of said housing.

31. A circuit breaker according to claim 26, said trip means comprising a stationary magnetic member and an armature supported with an air gap between said armature and stationary magnetic member, biasing means biasing said armature to an unattracted position, upon operation of said trip means said armature moving toward said stationary magnetic member against the bias of said biasing means to effect release of said releasable trip member, said externally accessible stop member being selectively positionable in said selected stopping position without changing the air gap between said armature and said magnetic member and without changing the bias of said biasing means on said armature, and said externally accessible stop member being selectively positionable in said selected stopping position to' prevent movement of said externally operable adjusting member to a position higher than a selected new high-current poles the associated armature being attracted to the' associated stationary magnetic member and moving against the bias of the associated biasing means to close the associated air gap during which movement the associated armature operates to effect movement of said common trip bar to effect release of said releasable trip member, said externally operable adjusting member being movable through a factoryset maximum range of movement from a minimum lowprotruding through said handle opening and being manually trip position only when said externally operable adjusting member is in a position that is not higher than said selected new high current trip position.

32. A circuit breaker according to claim 31, said circuit breaker being a multipole circuit breaker, a separate stationary contact and movable contact for each of said poles, a releasable trip member in only one pole releasable to effect automatic opening of all of said contacts, said current responsive trip means comprising a separate stationary magnetic member and armature for each pole, each of said armatures being supported for movement toward and away from the associated stationary magnetic member, a separate biasing means biasing each of said armatures away from the associated stationary magnetic member providing an air gap between the associated armature and associated stationary magnetic member, a trip bar common to all of said poles, upon the occurrence of overload current conditions in any of said operable to open and close said contacts, said housing having an adjusting member opening in the front thereof, said adjusting member being supported for movement about an axis extending in the direction from front to back in said housing, said adjusting member comprising an actuating part accessible for operation at said adjusting member opening, said housing having a plurality of stop-member openings therein the front thereof in proximity to said adjusting member opening, and said stop member being selectively positionable in a selected one of said stop-member openings into the path of movement of said stop part to stop movement of said adjusting member at the selected high-current trip position.

34. A circuit breaker according to claim 1, said circuit breaker being a multipole circuit breaker, a separate pair of said contacts for each of said poles, said trip means comprising a separate stationary magnetic member and separate armature for each of said poles, each of said armatures being supported for movement toward and away from the associated stationary magnetic member to diminish and enlarge an air gap, a common trip bar common to all of said poles, upon the occurrence of overload current conditions in any of said poles the associated armature being attracted to the associated stationary magnetic member and moving to operate said common trip bar to automatically trip said circuit breaker to simultaneously open the contacts of all of said poles, said adjusting means being selectively adjustable within a range of adjustment to simultaneously adjust the positions of said armatures to thereby adjust said trip means such that at a selected overload current within a range of overload currents in any of said pole units the armature in the overload currents in any of said pole units the armature in the overloaded pole unit will operate said common trip bar to automatically trip said breaker, and said limit means being a single limit means for selectively changing said range of adjustment without affecting the tripping action of any of said armatures in response to the adjusted position of said adjusting means such that at a given position of said adjusting means each of said armatures will trip said circuit breaker at the same predetermined overload current both before and after said range of adjustment is changed.

35. A circuit breaker according to claim 34, said adjusting means being externally accessible for operation from outside of said insulating housing, and said single limit means comprising an externally accessible limit member selectably movable to any of a plurality of limiting positions to change said range of adjustment. 

1. A circuit breaker comprising an insulating housing, a circuit breaker mechanism supported in said housing and comprising a pair of contacts, trip means operable automatically upon the occurrence of certain overload current conditions to automatically trip said circuit breaker opening said contacts, adjusting means selectively adjustable within a range of adjustment to adjust said trip means to trip said circuit breaker at a selected overload current within a range of overload currents, and limit means for selectively changing said range of adjustment without affecting the tripping action of said trip means in response to the adjusted position of said adjusting means such that at a given position of said adjusting means said trip means will trip said circuit breaker at the same predetermined overload current both before and after said range of adjustment is changed.
 2. A circuit breaker according to claim 1, said adjusting means being externally accessible for operation from outside of said installation housing, and said limit means comprising an externally accessible limit member selectively movable to any of a plurality of limiting positions to change said range of adjustment.
 3. A circuit breaker according to claim 1, said adjusting means comprising an adjusting member supported for adjusting movement about an axis, and said limit means comprising a limit member movable to a selected limiting position to stop said adjusTing movement of said adjusting member to prevent adjusting movement of said adjusting member past a selected position.
 4. A circuit breaker according to claim 1, said insulating housing having opening means therein, said adjusting means comprising an adjusting member externally accessible at said opening means and supported for adjusting movement, and said limit means comprising a limit member selectively movable from outside of said housing to any of a plurality of selected limiting positions to change said range of adjustment.
 5. A circuit breaker according to claim 1, said trip means comprising a stationary magnetic member and a movable armature structure in an initial position spaced from said stationary magnetic member by an air gap, upon the occurrence of an overload current above a predetermined value said armature structure being attracted to said stationary magnetic member and moving toward said stationary magnetic member to trip said circuit breaker, said adjusting means comprising an adjusting member supported for adjusting movement and being adjustably movable to change the initial position of said armature structure to change the dimension of said air gap, and said limit means being operable to change the range of adjusting movement of said adjusting member.
 6. A circuit breaker according to claim 5, said adjusting member being supported for adjusting movement about an axis, and said limit means comprising a limit member movable to a limiting position to limit said adjusting movement of said adjusting member.
 7. A circuit breaker according to claim 5, said adjusting member being externally accessible and operable from outside of said insulating housing, and said limit means comprising a limit member selectively positionable from outside of said housing in any of a plurality of positions to stop said adjusting movement of said adjusting member against movement past a position determined by the selected position of said adjusting member.
 8. A circuit breaker according to claim 6, said housing having a first opening in the front thereof, said adjusting member comprising an operating part accessible at said first opening to permit external operation of said adjusting member, said housing having a plurality of separate openings therein in proximity to said first opening, said adjusting member having a stop surface thereon, and said limit member being selectively positionable in any of said plurality of separate openings in a limiting position in the path of movement of said stop surface to limit adjusting movement of said adjusting member.
 9. A circuit breaker according to claim 8, said circuit breaker comprising a multipole circuit breaker, said insulating housing comprising a plurality of barriers separating said housing into a plurality of compartments in a side-by-side relationship, said circuit breaker mechanism comprising a pole unit in each of said compartments with each of said pole units comprising a separate pair of contacts, a separate trip means in each of said compartments, each of said separate trip means being operable upon the occurrence of certain overload current conditions to effect a tripping operation of said circuit breaker simultaneously opening all of said pairs of contacts, and said adjusting member being movable to simultaneously adjust all of said trip means.
 10. A circuit breaker according to claim 9, said adjusting member comprising an adjusting cam member having a cam surface thereon, a common adjusting bar cooperable with said cam surface and movable to simultaneously adjust said armature structures, said adjusting cam member having a slot therein open at the front of said adjusting member, a stationary stop member positioned in said slot, said adjusting cam member having a pair of stop surfaces for engaging said stationary stop member to limit movement of said adjusting cam member in both directions about said axis, and said limit member being positionable in said slot through any of said separate openings to coopErate with at least one of said stop surfaces to limit movement in at least one direction of said adjusting cam member.
 11. A circuit breaker comprising an insulating housing, a circuit breaker mechanism supported in said housing and comprising a pair of contacts, trip means operable automatically upon the occurrence of certain overload current conditions to trip said circuit breaker opening said contacts, externally accessible adjusting means adjustable from outside of said housing, said adjusting means being selectively adjustable within an initial range of adjustment to adjust said trip means to trip said circuit breaker at a selected overload current within a range of overload currents, and said circuit breaker being constructed and arranged to permit externally positionable limit means to be selectively positioned in any of a plurality of predetermined limiting positions to change said initial range of adjustment to a new range of adjustment within said initial range of adjustment.
 12. A circuit breaker according to claim 11, said adjusting means comprising an adjusting member supported for adjusting movement about an axis, said adjusting member comprising stop means, and said circuit breaker being constructed and arranged such that a limit member can be selectively positioned thereon in a selected position of said plurality of predetermined limiting positions in the path of movement of said stop means to limit adjusting movement of said adjusting member.
 13. A circuit breaker according to claim 12, said housing having opening means at the front thereof, said housing comprising a generally planar back, said adjusting member being supported for movement about an axis normal to said back and comprising an operating part accessible at said opening means in the front of said housing, said opening means in the front of said housing comprising a plurality of settings positioned such that when a limit member is positioned in a limiting position at any of said settings the limit member will be in the path of movement of said stop means to limit movement of said adjusting member about said axis.
 14. A circuit breaker according to claim 13, fixed projection means in said housing engaging said stop means of said adjusting member to limit movement in both directions of said adjusting member to provide said initial range of adjustment of said adjusting member, and said adjusting member comprising a cam member operating with a camming action upon rotation of said adjusting member to adjust the tripping characteristics of said circuit breaker.
 15. A circuit breaker according to claim 11, said housing comprising an insulating housing having a plurality of barriers therein forming a plurality of compartments in a side-by-side relationship, said circuit breaker comprising a multipole circuit breaker with a separate pole unit in each of said compartments, each of said pole units comprising a pair of cooperable contacts, said trip means comprising a separate trip device in each of said pole units, each of said separate trip device comprising a stationary magnetic member and a movable armature structure in an initial position spaced from the associated stationary magnetic member by an air gap, a common adjusting bar common to all of said pole units and movable to simultaneously move said armature structures to simultaneously adjust the initial positions of all said armature structures, said adjusting member and said adjusting bar structure comprising cooperating cam parts whereby upon adjusting movement of said adjusting member said adjusting bar structure will be cammed to vary the initial positions of all of said armature structures.
 16. A circuit breaker comprising an insulating housing, a circuit breaker mechanism supported in said housing and comprising a pair of contacts, trip means operable automatically upon the occurrence of certain overload current conditions to trip said circuit breaker opening said contacts, externally accessible adjusting means adjustable from outside of said housing, said adjusting means being factory set to provide selective adjustability within a range of adjustment from a low adjusted position to an initial high adjusted position to adjust said trip means to trip said circuit breaker at a selected overload current within a range of overload currents from a low-tripping overload current to an initial high-tripping overload current, and limit means comprising a limit member selectively positioned from outside of said housing in a selected position on said circuit breaker to provide a new high adjusted position of said adjusting means between said low adjusted position and said initial high adjusted position to provide that said adjusting means cannot be adjusted to a position higher than said new high adjusted position.
 17. A circuit breaker according to claim 16, said trip means comprising a stationary magnetic member and a movable armature structure, said armature structure being spaced from said stationary magnetic member by an air gap and being actuated toward said stationary magnetic member to trip said circuit breaker, said adjusting member being supported for movement about an axis and being movable between said low adjusted position and said high adjusted position, said adjusting member comprising stop means, and said limit member comprising a stop member selectively positioned in the path of movement of said stop means.
 18. A circuit breaker according to claim 17, said housing having opening means at the front thereof, said housing having a generally planar back, said adjusting member being supported for adjusting movement about an axis normal to the plane of said back, said adjusting member comprising an operating part accessible at said opening to permit external operation of said adjusting member, said adjusting member comprising stop means inside of said housing, said opening means at the front of said housing comprising a plurality of settings for receiving said limit member at any of said plurality of settings which limit member is positioned through a selected setting into the path of movement of said stop means to limit movement of said adjusting member.
 19. A circuit breaker comprising an insulating housing, a circuit breaker mechanism supported within said housing and comprising a pair of contacts, current responsive electromagnetic trip means comprising a stationary magnetic member and an armature supported with an air gap between said stationary magnetic member and armature, upon the occurrence of overload currents above a predetermined value said armature being attracted to said stationary magnetic member and moving to effect automatic opening of said contacts, adjusting means externally operable from outside said housing to adjust said armature to thereby adjust said air gap, said adjusting means being movable between an initial low limit low-trip adjusted position wherein said air gap is diminished and an initial high limit high-trip adjusted position wherein said air gap is enlarged, stop means in said housing providing the initial limits of movement of said adjusting means at said initial low limit low-trip adjusted position and said initial high limit high-trip adjusted position to thereby provide an initial range of adjustment of said adjusting means between said initial low limit low-trip adjusted position and said initial high limit high-trip adjusted position, and externally operable limit means selectively positionable on said circuit breaker to selectively provide a new high limit high-trip adjusted position between said initial low limit low-trip adjusted position and said initial high limit high-trip adjusted position.
 20. A circuit breaker according to claim 19, said insulating housing comprising a generally planar back, said adjusting means comprising an adjusting cam member movable about an axis normal to the plane of said back to adjust said armature with a camming action, said adjusting cam member comprising a stop part, and said limit means comprising a stop Member selectively positionable in the path of movement of said stop part.
 21. A circuit breaker according to claim 20, said insulating housing having an adjusting member opening therein, said adjusting cam member comprising an actuating part accessible for operation at said adjusting member opening, said insulating housing having a plurality of stop-member openings therein spaced around said adjusting member opening, and said stop member being selectively positionable in a selected one of said stop-member openings into the path of movement of said stop part.
 22. A circuit breaker according to claim 21, and said stop member being selectively and removable positionable in the selected stop-member opening.
 23. A circuit breaker according to claim 21, and said insulating housing and said stop member being constructed and arranged such that when said stop member is operatively positioned in the selected one of said stop-member openings said stop member is removable only by destruction of parts or disassembly of said housing.
 24. A circuit breaker according to claim 19, said circuit breaker being a multipole circuit breaker and comprising a pair of said contacts for each pole, a separate stationary magnetic member and armature for each pole, a common trip bar common to all of said poles, upon attraction of any of said armatures to the associated stationary magnetic member the attracted armature operating to effect movement of said common trip bar to effect automatic opening of said contacts, said adjusting means being a single adjusting means externally operable from outside said housing to simultaneously adjust all of said armatures to thereby simultaneously adjust all of the air gaps between said armatures and their associated stationary magnetic members, and said externally operable limit means being a single externally operable limit means selectively positionable to simultaneously selectively provide the new high limit high-trip adjusted positions of all of said armatures.
 25. A circuit breaker according to claim 24, said insulating housing having a handle opening in the front thereof, a handle protruding through said handle opening and being manually operable to simultaneously open and close the contacts of all of said poles, said adjusting means comprising an adjusting cam member supported for movement about an axis extending in the direction from front to back in said housing, said adjusting cam member being movable about said axis to simultaneously move all of said armatures with a camming action, said insulating housing having an adjusting member opening in the front thereof, said adjusting cam member comprising an actuating part accessible for operation at said adjusting member opening, said adjusting cam member comprising a stop part, said insulating housing having a plurality of stop-member openings in the front thereof spaced around said adjusting member opening, and said limit means comprising a stop member selectively positionable in a selected one of said stop-member openings into the path of movement of said stop part.
 26. A circuit breaker comprising a housing, a circuit breaker mechanism supported in said housing, said mechanism comprising a stationary contact, a movable contact, a releasable trip member releasable to effect automatic opening of said contacts, current responsive trip means automatically operable in response to overload current conditions to effect release of said releasable trip member, an externally operable adjusting member movable through a factory-set maximum range of movement from a minimum low-current trip position to a maximum high-current trip position to adjust said trip means, and an externally accessible stop member selectively positionable in a selected stopping position selectable from a plurality of stopping positions between said minimum low-current trip position and said maximum high-current trip position to prevent movement of said externally operable adjusting member to a position higher than a selected new high-cuRrent trip position between said minimum low-current trip position and said maximum high-current trip position.
 27. A circuit breaker according to claim 26, said adjusting means comprising an adjusting member supported for adjusting movement about an axis, said adjusting member comprising a stop part, and said externally accessible stop member being selectively positionable in the path of movement of said stop means to stop movement of said adjusting member at the selected new high-current trip position.
 28. A circuit breaker according to claim 27, said housing having a handle opening in the front thereof, a handle protruding through said handle opening and being manually operable to open and close said contacts, said housing having an adjusting member opening in the front thereof, said adjusting member being supported for adjusting movement about an axis extending in the direction from front to back in said housing, said adjusting member comprising an actuating part accessible for operation at said adjusting member opening, said housing having a plurality of stop-member openings therein in proximity to said adjusting member opening, and said stop member being selectively positionable in a selected one of said stop-member openings into the path of movement of said stop part.
 29. A circuit breaker according to claim 28, and said stop member being selectively and removably positionable in the selected stop-member opening.
 30. A circuit breaker according to claim 28, and said housing and said stop member being constructed and arranged such that when said stop member is operatively positioned in the selected one of said stop-member openings said stop member is removable only by destruction of parts or disassembly of said housing.
 31. A circuit breaker according to claim 26, said trip means comprising a stationary magnetic member and an armature supported with an air gap between said armature and stationary magnetic member, biasing means biasing said armature to an unattracted position, upon operation of said trip means said armature moving toward said stationary magnetic member against the bias of said biasing means to effect release of said releasable trip member, said externally accessible stop member being selectively positionable in said selected stopping position without changing the air gap between said armature and said magnetic member and without changing the bias of said biasing means on said armature, and said externally accessible stop member being selectively positionable in said selected stopping position to prevent movement of said externally operable adjusting member to a position higher than a selected new high-current trip position only when said externally operable adjusting member is in a position that is not higher than said selected new high-current trip position.
 32. A circuit breaker according to claim 31, said circuit breaker being a multipole circuit breaker, a separate stationary contact and movable contact for each of said poles, a releasable trip member in only one pole releasable to effect automatic opening of all of said contacts, said current responsive trip means comprising a separate stationary magnetic member and armature for each pole, each of said armatures being supported for movement toward and away from the associated stationary magnetic member, a separate biasing means biasing each of said armatures away from the associated stationary magnetic member providing an air gap between the associated armature and associated stationary magnetic member, a trip bar common to all of said poles, upon the occurrence of overload current conditions in any of said poles the associated armature being attracted to the associated stationary magnetic member and moving against the bias of the associated biasing means to close the associated air gap during which movement the associated armature operates to effect movement of said common trip bar to effect release of said releasable trip member, said externally operable adjusting Member being movable through a factory-set maximum range of movement from a minimum low-current trip position to a maximum high-current trip position to simultaneously move said armatures to thereby simultaneously adjust said air gaps from diminished air gap positions to enlarged air gap positions, said externally accessible stop member being selectively positionable in said selected stopping position without changing the dimensions of said air gaps or the bias of said biasing means of said armatures at the adjusted positions of said adjusting member.
 33. A circuit breaker according to claim 32, said housing having a handle opening in the front thereof, a handle protruding through said handle opening and being manually operable to open and close said contacts, said housing having an adjusting member opening in the front thereof, said adjusting member being supported for movement about an axis extending in the direction from front to back in said housing, said adjusting member comprising an actuating part accessible for operation at said adjusting member opening, said housing having a plurality of stop-member openings therein the front thereof in proximity to said adjusting member opening, and said stop member being selectively positionable in a selected one of said stop-member openings into the path of movement of said stop part to stop movement of said adjusting member at the selected high-current trip position.
 34. A circuit breaker according to claim 1, said circuit breaker being a multipole circuit breaker, a separate pair of said contacts for each of said poles, said trip means comprising a separate stationary magnetic member and separate armature for each of said poles, each of said armatures being supported for movement toward and away from the associated stationary magnetic member to diminish and enlarge an air gap, a common trip bar common to all of said poles, upon the occurrence of overload current conditions in any of said poles the associated armature being attracted to the associated stationary magnetic member and moving to operate said common trip bar to automatically trip said circuit breaker to simultaneously open the contacts of all of said poles, said adjusting means being selectively adjustable within a range of adjustment to simultaneously adjust the positions of said armatures to thereby adjust said trip means such that at a selected overload current within a range of overload currents in any of said pole units the armature in the overload currents in any of said pole units the armature in the overloaded pole unit will operate said common trip bar to automatically trip said breaker, and said limit means being a single limit means for selectively changing said range of adjustment without affecting the tripping action of any of said armatures in response to the adjusted position of said adjusting means such that at a given position of said adjusting means each of said armatures will trip said circuit breaker at the same predetermined overload current both before and after said range of adjustment is changed.
 35. A circuit breaker according to claim 34, said adjusting means being externally accessible for operation from outside of said insulating housing, and said single limit means comprising an externally accessible limit member selectably movable to any of a plurality of limiting positions to change said range of adjustment. 